The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingIntake air temperature sensor gradient too high
Description
The intake air temperature (iat) sensor, mounted on the mass air flow (maf)
meter, monitors the iat.
The iat sensor has a built-in thermistor with a resistance that varies according
to the temperature of the
intake air. When the iat is low, the resistance of the thermist ...
Removal and installation of fuel control
parts
Place for removing and installing fuel
system parts
Work in a location with good air ventilation that
does not have welders, grinders, drills, electric
motors, stoves, or any other ignition sources.
Never work in a pit or near a pit as vaporized
fuel will collect in those places.
...
Push switch / key unlock warning switch malfunction
Description
This dtc is output if the transponder key ecu does not detect that the unlock
warning switch is on even
when the ignition switch is on. Under normal conditions, the unlock warning
switch is on when the
ignition switch is on.
Wiring diagram
Inspection procedure
Re ...